Gravitational Lensing
As light flies through the Universe, we might suppose that it will travel along a straight line. This turns out not to be the case: light rays can be bent by the effects of gravity in the Universe. Wherever there is a clump of matter, there is a slight gravitational distortion of space and time; the light that passes near such a clump will therefore be deflected. We call this bending of light “Gravitational Lensing”.
Gravitational lensing by a cluster of galaxies. The large arc-like objects are galaxy images which have been severely gravitationally lensed. Credit: NASA, ESA, the Hubble SM4 ERO Team, and ST-ECF
This leads to striking images of distant galaxies, where their appearance has been stretched and magnified by gravitational lensing.
ICG researchers study the appearance of distance galaxies, to understand the source of the gravitational lensing. We expect this to be the dark matter between us and the galaxies; also, the amount of lensing can tell us about the behaviour of gravity itself.
Recent research highlights include:
– a study of a new type of lensing in the Universe:
Anti-lensing: the bright side of voids, Phys. Rev. Lett. 110, 021302 (2013), Krzysztof Bolejko, Chris Clarkson, Roy Maartens, David Bacon, Nikolai Meures, Emma Beynon
– a test of the theory of gravity, combining gravitational lensing and other cosmological measurements:
Probing modifications of General Relativity using current cosmological observations, Phys.Rev.D81:103510,2010, Gong-Bo Zhao, Tommaso Giannantonio, Levon Pogosian, Alessandra Silvestri, David J. Bacon, Kazuya Koyama, Robert C. Nichol , Yong-Seon Song
– predictions for gravitational lensing in different theories of gravity:
Weak lensing predictions for modified gravities at non-linear scales, Mon. Not. R. Astron. Soc. 403, 353-362 (2010), Emma Beynon, David J. Bacon, Kazuya Koyama
– a test of the theory of gravity, combining gravitational lensing and the velocity of galaxies:
Complementarity of Weak Lensing and Peculiar Velocity Measurements in Testing General Relativity, Phys.Rev. D84 (2011) 083523, Yong-Seon Song, Gong-Bo Zhao, David Bacon, Kazuya Koyama, Robert C Nichol, Levon Pogosian
